The video that real estate executive Ryan Nelson produced on a weekday evening last April, after climbing to a rooftop in Midtown West and filming buses crawl by a neighboring parking lot, may be the least exciting movie ever made.

Over the course of 40 minutes, as the sun sank over Manhattan, he documented the progress of a Lakeland bus from who knows where as it went past a parking lot on 36th Street and 10th Avenue on its way to the Port Authority Bus Terminal six blocks north. It moved all of one block.

The Port Authority terminal, the nation’s largest bus facility, is most famous for its poor aesthetics and general decrepitude: its low ceilings and tiled-bathroom affect, its heat in the summer, its atmosphere so starved of anything resembling human warmth that the plastic trees in the north wing’s basement actually are a balm to the eye.

New Jersey residents make up 12 percent of Manhattan’s workforce, and every morning rush hour, more than 83,000 of them pass through the Port Authority terminal on their way to work. That compares to about 62,000 on PATH (both uptown and downtown) and 45,000 who come in by way of Penn Station.

What that means, in practice, is long lines, interminable delays and endless queues of buses idling their way through New York City neighborhoods, blocking intersections and pedestrian crossings, gas stations and parking lots.

“There are entire swaths of the district which are completely occupied by bus operations,” said Christine Berthet, who chairs Community Board 4.

In recent weeks, the plight of the nation’s largest bus terminal has begun to play a supporting role in stories about the waywardness of the once proudly technocratic Port Authority of New York and New Jersey, the organization that controls the bus terminal and shares its name.

Ken Lipper, the Port commissioner who took advantage of the post-Bridgegate turmoil to decry and ultimately foil its plans to deepen a commitment to a risky real estate development at the World Trade Center site, argued that the authority’s time and money could be better spent resurrecting the bus terminal.

New Jersey legislative leaders recently responded to their angst-ridden constituents by demanding the Port do something about its deteriorating physical plant, and won a commitment of $90 million for some still-to-be-determined repairs.

It’s not clear where the Port Authority is finding that extra $90 million. (“I wish I was in a business where I could find $90 million,” said New Jersey State Senate majority leader Loretta Weinberg. “How do you find $90 million?”)

But the Port Authority did describe the money as an “initial investment,” which was probably wise, because to people familiar with the bus terminal and its problems, that $90 million is a pittance, particularly when compared to the $1.5 billion the Port will spend to extend the PATH less than two miles to Newark, so that the three-seat ride from lower Manhattan to Newark airport can become a two-seat ride instead.

Veronica Vanterpool, executive director of the Tri-State Transportation Campaign, characterizes the dichotomy this way: “$1.5 billion for an extension of redundant service and $90 million toward bus facilities that carry 38 percent of people crossing the Hudson every day? It’s absurd.”

In a way, the best comparable for the plight facing the bus terminal is the plight facing the rail station eight blocks south.

“It’s just like Penn Station,” said Vishaan Chakrabarti, a partner at SHoP Architects and a professor at Columbia. “Now we have these two aging facilities that are really a reflection of a bygone era that are serving hundreds of thousands of people a day. And I think both need to be rethought and redeveloped.”

NEW YORK CITY HAS HAD THIS PROBLEM BEFORE, in the days when the Port Authority had a good reputation and its bureaucrats were capable of carrying out big plans.

In 1937, the Port Authority finished the first tube of the Lincoln Tunnel. Interstate buses, which had to that point been limited to the (also recently completed) George Washington Bridge and the Holland Tunnel, soon began converging on Midtown in a serious way.

“By 1939, the earlier trickle of interstate buses had grown to 1,500 buses each day,” wrote Jameson Doig in his authoritative history of the Port Authority, Empire on the Hudson.

The river of buses would exit the Lincoln Tunnel and then break into streams coursing through Manhattan to each of eight separate bus stations, making stops along the way.

Urban planners and the Port Authority agreed: New York City needed to build one terminal to replace the existing eight, and to put it at the mouth from which all that bus traffic was spewing: the Lincoln Tunnel.

A decade of bitter politicking ensued.

A short list of Port executive director August Tobin’s seemingly insurmountable challenges included Robert Moses, who was then working for Mayor LaGuardia and who fervently opposed the terminal, for reasons that Doig suggests were of a largely territorial nature.

Tobin also had to find a way to relocate the 640 families and 140 businesses then occupying the site of the future bus station. He ended up having to build replacement housing to do so.

As all this was going on, the river of interstate buses swelled to more than 2,500 a day.

Nevertheless, by 1950, the Port Authority had relocated all those families and business and built a unified bus terminal. It took buses off the street, it relieved congestion, and by and large it pleased the city’s editorial boards.

Even then, it was not considered an attractive building, at least to historian Lewis Mumford, who called the finished product “a humdrum job of engineering concealed behind a mask of wholly perfunctory masonry.”

But it was functional, at least for a while.

As the New York Herald Tribune presciently editorialized in 1950, “The Port Authority Bus Terminal will promptly be taken for granted, with little thought that this piece of progress did not happen quite automatically. It took years of struggle.”

SINCE 1950, THE TERMINAL HAS UNDERGONE ONE MAJOR expansion, and it hasn’t been nearly enough.

More than 9,000 buses cross the Hudson River each day and spill into Manhattan’s west side. More than 7,500 berth at the bus terminal, according to the Port Authority. Another 1,500 or so pick up passengers on the street, according to Community Board 4, which encompasses the terminal.

That’s the same number of buses that in the 1940s prompted the Port to recommend the creation of a unified bus terminal, and the situation is not expected to improve, thanks to a combination of New Jersey governor Chris Christie’s unilateral decision to halt a bottleneck-easing tunnel project, an ongoing population boom in the metropolitan area, and the construction of Hudson Yards, a 17 million-square-foot development to the terminal’s southwest.

That is, things are unlikely to get significantly better until New York City does as places like Denver, Madrid and Santiago, Chile have done by investing in a new or substantially overhauled hub.

There’s a reason those other cities have made investments in bus transportation.

“Buses may not be sexy, but there’s a lot of things about them that are very good,” said Chakrabarti. “They’re flexible. You can change a route very easily. You can respond to new demand patterns.”

But the flexibility of a bus system depends on the nimbleness of the agency that runs it. And the contemporary Port Authority has been no match, in terms of its ability to get things done, to the glory-days version.

The Port has been casting about for a solution to its problem, but never quite finding one, since 1996, when the authority began talking to developers about selling the air rights over the terminal, enabling the developer to build a tower there and helping finance a restoration of the terminal underneath. In 1999, the Port signed a contract with real estate firm Vornado and the Lawrence Ruben Company to do just that.

Vornado was never able to make the project work and ultimately abandoned the idea.

Now, the Port Authority is taking part in a “master study” and investigating various options, including erecting a bus garage to the terminal’s west, which at the very least would allow some buses to stay in Manhattan after they drop commuters off at the terminal, rather than forcing them to return to New Jersey and then come back again in the evening, before recrossing the river.

The authority is also once again looking into the sale of air rights over the bus terminal.

Developers differ on whether that’s such a good idea.

“I can tell you what I don’t think should happen,” said Douglas Durst, who’s developing One World Trade Center with the Port Authority downtown. “I don’t think it should become an office building.”

“Are you aware of Eleven Times Square, and the difficulty they’ve had renting?” he asked, referring to the office tower directly to the Port Authority’s east, which was built on spec during the recession and has had trouble filling up. “Seven Bryant Park hasn’t leased any space. The numbers you need to lease new office space are much higher than the market is allowing right now.”

George Lancaster, the spokesman for 7 Bryant Park developer Hines, said that “there are a few big prospects that are very interested and engaged in active discussions,” and the company has “total confidence in the Midtown market.”

In 2001, the Port Authority of New York and New Jersey floated another idea, one that also never went anywhere: It voted to stop subsidizing New Jersey Transit’s use of the bus terminal.

Every time a Greyhound bus leaves the Port Authority, it is charged $45.29. Every time a New Jersey Transit bus leaves the terminal, it’s charged $2.48.

New Jersey Transit is the bus terminal’s biggest commuter customer.

“However, in an effort to encourage the general economic growth of the region, the increases were subsequently suspended,” according to the Navigant report ordered by Governors Christie and Cuomo, following a furor over the toll hikes that they, unconvincingly, claimed ignorance of back in 2011.

The report went on: “As a result, in 2011 the bus terminal lost $62 million of net operating revenue.”

Last year it lost $100 million.

According to the Citizens Budget Commission, that amount of revenue could be used to underwrite more than $1 billion in bond financing the terminal’s repair. And according to a knowledgeable source, the Port is again exploring the prospect.

“Everybody, including the New Jersey Transit customers, wants a better station and they should, but perhaps they should be willing to chip in a little bit for the cost,” said Carol Kellermann, the commission’s president.

“As the largest tenant, NJ TRANSIT pays $5 million in fees annually for use of the terminal and an additional $11 million dollars in tolls at the crossings,” said NJ Transit spokesman William Smith. “We are actively working with the Port Authority and our partners in government in exploring and identifying short and long-term solutions to improve the experience for everyone who utilizes the terminal.”

There’s an idea that’s even more radical than either of those, and even less likely.

In Berthet’s ideal world, and also the Real Estate Board of New York’s, New Jersey commuters would board an extension of the number 7 train from Secaucus into Manhattan. Michael Bloomberg took a liking to that idea, and advocated for it in his third term as a means of alleviating ever-worsening cross-Hudson congestion.